# std::towupper

From cppreference.com
< cpp‎ | string‎ | wide

Defined in header `<cwctype>` |  |
std::wint_t towupper( std::wint_t ch ); |  |

Converts the given wide character to uppercase, if possible.

If the value of ch is neither representable as a wchar_t nor equal to the value of the macro WEOF, the behavior is undefined.

### Parameters

ch | - | wide character to be converted

### Return value

Uppercase version of ch or unmodified ch if no uppercase version is listed in the current C locale.

### Notes

Only 1:1 character mapping can be performed by this function, e.g. the uppercase form of 'ß' is (with some exceptions) the two-character string "SS", which cannot be obtained by `std::towupper`.

ISO 30112 specifies which pairs of Unicode characters are included in this mapping.

### Example

The latin letter 'ſ' (U+017F) is the alternative lowercase form of 'S' (U+0053).

Run this code

    #include <clocale>
    #include <cwctype>
    #include <iostream>

    int main()
    {
        wchar_t c = L'\u017f'; // Latin small letter Long S ('ſ')

        std::cout << std::hex << std::showbase;
        std::cout << "in the default locale, towupper("
                  << static_cast<std::wint_t>(c) << ") = "
                  << std::towupper(c) << '\n';

        std::setlocale(LC_ALL, "en_US.utf8");
        std::cout << "in Unicode locale, towupper("
                  << static_cast<std::wint_t>(c) << ") = "
                  << std::towupper(c) << '\n';
    }

Output:

    in the default locale, towupper(0x17f) = 0x17f
    in Unicode locale, towupper(0x17f) = 0x53

### See also

towlower | converts a wide character to lowercase (function)
toupper(std::locale) | converts a character to uppercase using the ctype facet of a locale (function template)
toupper | converts a character to uppercase (function)
C documentation for towupper

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